A system includes a rack with shelves and one or more groups of shelf-mountable electrical systems. Each of at least two of the shelf-mountable electrical systems includes one or more chassis, shelf computing devices, a shelf power supply mechanism, and one or more power-pooling bus elements. For at least one of the groups, a power-pooling bus element of at least one shelf-mountable electrical systems is electrically coupled to a power pooling bus element of at least one other of the shelf-mountable electrical systems in the group such that the power-pooling bus elements form an inter-shelf power-pooling bus for one or more of the computing devices in the group.